1. Field
The present disclosure relates generally to a wireless transceiver. More specifically, the present disclosure relates to an asymmetrical wireless transceiver that enables the utilization of the TV white space spectrum.
2. Related Art
A recent decision of the Federal Communications Commission (FCC) has allowed unlicensed broadcasting devices access to “white spaces” in the television spectrum, prompting the development of the “WhiteFi” technology and white-spaces devices. Unlike traditional WiFi, which operates most commonly at 2.4 GHz and 5.0 GHz, white-spaces devices operate over 30 separate 6 MHz TV channels (freed after the conversion to digital TV) in the ultra-high frequency (UHF) band.
In order to protect licensed TV broadcasters from harmful interference, the FCC has required that the level of interference from adjacent channels needs to be at least 55 dB below the highest average power in the channel. This requirement limits the amount of distortion or nonlinearity that can be tolerated by the power amplifier (PA), because an amplifier that compresses its input or has a nonlinear input/output relationship causes the output signal to splatter onto adjacent frequencies. As a result, the required amount of backed-off power from the P1dB compression point can be significantly large, thus resulting in a relatively low PA efficiency. For example, to meet the requirement of the FCC spectral mask, the PA needs to have a P1dB point of approximately 35 dBm (with 18 dB back-off margin). This can lead to rapid battery drainage of mobile devices.